Pointing input system and method using one or more array sensors

ABSTRACT

In a pointing input system and method, a pointer applies a light spot on a screen, an array sensor shoots on the screen to generate a first data for an identification system to retrieve a second data therefrom, the second data includes the position information of the light spot for an information system to apply a correlated output on the screen. The second data is generated based on an optical distortion parameter and a spatial rotation and displacement parameter determined by an alignment procedure that comprises applying an input for alignment on the screen for the array sensor to shoot to generate an alignment data, and comparing the alignment data with a reference data.

FIELD OF THE INVENTION

The present invention is related generally to a system and method fordirect inputs on a screen and more particularly, to a pointing inputsystem and method for an information system.

BACKGROUND OF THE INVENTION

Current input apparatus available for information systems includeskeyboard, mouse, trackball, light pen, and touch panel. The trackball isnot suitable to be used for writing on an upright screen. The light penis only available for the inputs on a scanning screen such asCathode-Ray Tube (CRT) screen, but not for the inputs on a highresolution screen. The touch panel is disadvantageous to alignment andportability for larger-scale screens. Due to the significant barrel orpincushion distortion of the optical lens, the input systems usingconventional sensors may often suffer the alignment degradation causedby the mistakes or unintentional touches to the equipment, and even haveto be suspended during its use accordingly. Therefore, single keyboardand/or single mouse installed on a computer system is still relied oncurrently for the inputs to an information system using an uprightlarge-scale screen. However, single input apparatus is inconvenient foruse in the situation where multiple inputs from several persons oropinion exchanges between several persons are required.

Therefore, it is desired a pointing input system and method easy foralignment, capable of precise positioning, and available for highresolution applications.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a pointing inputsystem and method for an information system.

Another object of the present invention is to provide a pointing inputsystem and method for direct inputs on an upright large-scale screen.

In a pointing input method according to the present invention, a lightspot is applied on a screen, the screen is shot by an array sensor togenerate a first data, a second data including the position informationof the light spot is retrieved from the first data, and an outputcorresponding to the light spot is applied on the screen. The seconddata is generated from the first data based on an optical distortionparameter and a spatial rotation and displacement parameter determinedby an alignment procedure that comprises applying an input for alignmenton the screen for the array sensor to shoot on the screen to generate analignment data, and comparing the alignment data with a reference data.

In a pointing input system according to the present invention, a firstbuffer stores a reference data and an alignment data generated in analignment procedure, a processor analyzes the alignment data andcompares the alignment data with the reference data to obtain an opticaldistortion parameter and a spatial rotation and displacement parameterof an optical lens in an array sensor that is used to shoot on a screenin the alignment procedure, a second buffer stores the opticaldistortion parameter and spatial rotation and displacement parameter, apointer applies a light spot on the screen for the array sensor to shootto generate a first data, an identification system retrieves a seconddata including the position information of the light spot from the firstdata, and a display system applies an output corresponding to the lightspot on the screen.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, features and advantages of the presentinvention will become apparent to those skilled in the art uponconsideration of the following description of the preferred embodimentsof the present invention taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 shows a space where an array sensor is used;

FIG. 2 shows a first embodiment of an alignment procedure according tothe present invention;

FIG. 3 shows three exemplary test patterns for the alignment procedureillustrated in FIG. 2;

FIG. 4 shows a second embodiment of an alignment procedure according tothe present invention;

FIG. 5 shows a first embodiment of a pointing input system according tothe present invention;

FIG. 6 shows a second embodiment of a pointing input system according tothe present invention;

FIG. 7 shows a third embodiment of a pointing input system according tothe present invention;

FIG. 8 shows a fourth embodiment of a pointing input system according tothe present invention;

FIG. 9 shows an embodiment of hardware for a pointing input systemaccording to the present invention;

FIG. 10 shows a flowchart of an alignment procedure for a pointing inputsystem according to the present invention;

FIG. 11 shows a flowchart of a pointing input method according to thepresent invention;

FIG. 12 shows an embodiment of a pointer available for a pointing inputsystem according to the present invention; and

FIG. 13 shows an illustrative diagram for an identification of a lightspot.

DETAILED DESCRIPTION OF THE INVENTION

Transformation Between Two Coordinate Systems

In a space 10, as shown in FIG. 1, an array sensor 12 has a focus plane14 apart from the array sensor 12 with a distance L, a point M(X, Y, Z)in the space 10 is mapped to a point m(x, y, z)=m(X×L/Z, Y×L/Z, L) onthe focus plane 14, where X, Y, Z, x, y, and z are the coordinates ofthe respective points M and m. If an optical lens 16 for mapping ontothe array sensor 12 has an optical distortion, due to the polarsymmetric to the central point of the optical lens 16, the spatialrelationship between the optical lens 16 and the original point of thearray sensor 12 is first determined, and further to transform theoriginal coordinates to a polar coordinates as in the following$\begin{matrix}{{m = {{A\lbrack{RT}\rbrack}M}},} & \left( {{EQ}\text{-}1} \right) \\{{A = \begin{bmatrix}f_{x} & 0 & c_{x} \\0 & f_{y} & c_{y} \\0 & 0 & 1\end{bmatrix}},} & \left( {{EQ}\text{-}2} \right) \\{{R = \begin{bmatrix}r_{11} & r_{12} & r_{13} \\r_{21} & r_{22} & r_{23} \\r_{31} & r_{32} & r_{33}\end{bmatrix}},{T = \begin{bmatrix}t_{1} \\t_{2} \\t_{3}\end{bmatrix}},{and}} & \left( {{EQ}\text{-}3} \right) \\{{\hat{x} = {x + {x\left\lbrack {{k_{1}r^{2}} + {k_{2}r^{4}}} \right\rbrack} + \left\lbrack {{2p_{1}{xy}} + {p_{2}\left( {r^{2} + {2x^{2}}} \right)}} \right\rbrack}},{\hat{y} = {y + {y\left\lbrack {{k_{1}r^{2}} + {k_{2}r^{4}}} \right\rbrack} + \left\lbrack {{2p_{2}{xy}} + {p_{2}\left( {r^{2} + {2y^{2}}} \right)}} \right\rbrack}},{r^{2} = x^{{2\quad + y^{2}},}}} & \left( {{EQ}\text{-}4} \right)\end{matrix}$where matrix A is the transformation matrix of the combination of thearray sensor 12 and optical lens 16, f_(x) and f_(y) are the focusdistances along the X axis and Y axis, c_(x) and c_(y) are thecoordinates of the central point of the image mapped by the optical lens16 onto the array sensor 12, x and y are the coordinates at the arraysensor 12 with the point (c_(x), c_(y)) as the central point, matrixes Rand T are the transformation matrix resulted from the rotation anddisplacement in the space 10, k₁ is the second-order radial distortion,k₂ is the fourth-order radial distortion, p₁ is the second-order tangentdistortion, and p₂ is the fourth-order tangent distortion.

First Embodiment of Alignment Procedure

FIG. 2 shows an alignment procedure 20 a for a pointing input systemapplied for an information system using front projection. To identifythe shooting range of an array sensor 22 a on a screen 21 a, it is useda viewing window 25 a on the array sensor 22 a to inspect on the screen21 a or light beams emitted by high intensity Light-Emitting Diodes(LEDs) or laser diodes 24 a on the array sensor 22 a to project lightspots on the screen 21 a. Then an input for alignment is applied on thescreen 21 a, for example displaying a test pattern on the screen 21 a bya front projector 23 a. FIG. 3 shows three exemplary test patterns,chessboard pattern 30, square pattern 32, and cross pattern 34. However,the test pattern may be other predetermined patterns in some otherembodiments. The array sensor 22 a shoots the test pattern on the screen21 a to generate an alignment data 26 a that is further sent to acomputer system 27 a. The alignment data 26 a includes the imageinformation of the test pattern generated by the array sensor 22 a, andan image recognizing software and spatial displacement and rotationcalculation tool programs 28 a are running on the computer system 27 ato analyze the relative positions and three-dimensional relationship ofseveral points on the test pattern from the alignment data 26 a and areference data. Briefly, the alignment data 26 a is the one obtained byshifting and rotating the original test pattern in a three-dimensionalspace, and by comparing the alignment data 26 a with the reference data,the spatial relationship between the screen 21 a and array sensor 22 ais determined. As a result, a spatial rotation and displacementparameter is obtained, which describes the spatial transformationbetween the screen 21 a and array sensor 22 a. By comparing the relativepositions between the several points, in association with the lensdistortion equation such as EQ-4, it is determined an optical distortionparameter for the optical lens in the array sensor 22 a to furthermodify the spatial relationship between the screen 21 a and array sensor22 a. The screen 21 a may have a planar surface, a regularly curvedsurface, or an irregularly curved surface. In the circumstances ofregularly or irregularly curved surface such that the arithmeticcomputation for the spatial transformation is too complicated, bilinearinterpolation may be used to calculate the coordinates of the severalpoints in the alignment data 26 a and reference data to conduct thespatial transformation relationship. The parameters generated by thealignment procedure 20 a pictures the spatial relationship between thescreen 21 a and array sensor 22 a and the optical distortion of theoptical lens in the array sensor 22 a.

Second Embodiment of Alignment Procedure

FIG. 4 shows an alignment procedure 20 b for a pointing input systemapplied for an information system using rear projection. To identify theshooting range of an array sensor 22 b on a screen 21 b, it is used aviewing window 25 b on the array sensor 22 b to inspect on the screen 21b or light beams emitted by high intensity LEDs or laser diodes 26 b onthe array sensor 22 b to project light spots on the screen 21 b. Then aninput for alignment is applied on the screen 21 b, for example applyinglight spots at several specific positions on the screen 21 a by apointer 24 b. The light spot is reflected to the array sensor 22 b by amirror 27 b. The intensive light from a rear projector 23 b to projecton the screen 21 b may be reflected by the mirror 27 b to generatehighly bright spots on the array sensor 22 b, causing the identificationmore difficult. Therefore, an optical filter 28 b is arranged in frontof the array sensor 22 b to filter out the intensive light from theprojector 23 b, and thereby to specify the light source of the pointer24 b from that of the projector 23 b. The light spots for alignment areshot by the array sensor 22 b to generate an alignment data 29 bincluding the image information of the light spots on the screen 21 b.The alignment data 29 b is sent to a computer system 30 b, where animage recognizing software and spatial displacement and rotationcalculation tool programs 31 b are running to analyze the relativepositions and three-dimensional relationship of several points in thealignment data 29 b and a reference data. By comparing with thereference data that includes the spatial information regarding to thespecific positions on the screen 21 b to be applied with the lightspots, a spatial rotation and displacement parameter is obtained topicture the spatial transformation between the screen 21 b and arraysensor 22 b. The screen 21 b may have a planar surface, a regularlycurved surface, or an irregularly curved surface. In the circumstancesof regularly or irregularly curved surface such that the arithmeticcomputation for the spatial transformation is too complicated, bilinearinterpolation may be used to calculate the coordinates of the severalpoints in the alignment data 26 a and reference data to conduct thespatial transformation relationship. The parameters generated by thealignment procedure 20 b pictures the spatial relationship between thescreen 21 b and array sensor 22 b.

First Embodiment of Pointing Input System

FIG. 5 shows a pointing input system 40 applied for an informationsystem using single front projector 41 and single array sensor 42. Inthe pointing input system 40, after an alignment procedure 20 aillustrated in FIG. 2, a pointer 46 could be used for direct inputs on ascreen 43. The light spot 47 projected by the pointer 42 on the screen43 is shot by the array sensor 42 to generate a first data including theimage information of the light spot 47 sent to a computer system 44,where an identification system 49 running on the computer system 44retrieves a second data including the position information of the lightspot 47 from the first data based on the optical distortion parameterand spatial rotation and displacement parameter that are obtained by thealignment procedure 20 a. The second data is provided for the projector41 to display a correlated output on the screen 43. In FIG. 5, thecorrelated output is an image of the light spot 47, while in otherembodiments, it may be a cursor moved to the position of the light spot47, or another output generated in response to a command from thepointer 46. In the system 40, an optical lens 45 and an optical filter48 are arranged in front of the array sensor 42 for mapping onto thearray sensor 42 and filtering out the optical noise for the array sensor42, thereby enhancing the identification carried out by the computersystem 44.

Second Embodiment of Pointing Input System

FIG. 6 shows a pointing input system 50 applied for an informationsystem using single front projector 51 and multiple array sensors 52.After an alignment procedure 20 a illustrated in FIG. 2, the system 50allows a pointer 46 to directly input on a screen 53. The array sensors52 are arranged in different directions to shoot on the screen 53, andthus, if one of them is unable to shoot the light spot on the screen 53properly, another is switched instead to shoot on the screen 53, so asto achieve the purpose of full viewing angle without any loss. Sinceseveral array sensors 52 are provided in the system 50, the screen 53may have very large area for display. The other operations are referredto the first embodiment 40 illustrated in FIG. 5. The identificationsystem is not shown in FIG. 6 for simplicity.

Third Embodiment of Pointing Input System

FIG. 7 shows a pointing input system 60 applied for an informationsystem using multiple front projectors 61, multiple array sensors 62,and multiple pointers 63. In this system 60, a screen 64 is defined tohave several projection regions each one is responsible by a projector61 to display thereon and by an array sensor 62 to shoot thereon, so asto improve the resolution. After an alignment procedure 20 a illustratedin FIG. 2, the pointers 63 are allowed in this system 60 for directinputs on the screen 64. By using the pointers 63, it is achievedmultiple inputs from several persons or opinion exchanges betweenseveral persons, without any additional equipments. Using the pointers63 for direct inputs on the screen 63 may be referred to the firstembodiment 40 illustrated in FIG. 5. The identification system is notshown in FIG. 7 for simplicity.

Fourth Embodiment of Pointing Input System

FIG. 8 shows a pointing input system 70 applied for an informationsystem using rear projection. After an alignment procedure 20 billustrated in FIG. 4, it is allowed direct inputs on a screen 73 by apointer 75 in this system 70. With a mirror 74, a rear projector 71projects an image reflected on the screen 73. The mirror 74 also assistsan array sensor 72 in shooting on the screen 73. The light spot 76projected by the pointer 75 on the screen is reflected by the mirror 74to the array sensor 72 to generate a first data including the imageinformation of the light spot 76. The first data is sent to a computersystem (not shown) for an identification system to retrieve a seconddata including the position information of the light spot 76 from thefirst data based on the spatial rotation and displacement parameter thatare obtained in the alignment procedure 20 b. The second data isprovided for the projector 71 to display a correlated output on thescreen 73. In FIG. 8, the correlated output is an image of the lightspot 76, while in other embodiments, it may be a cursor moved to theposition of the light spot 76, or another output generated in responseto a command from the pointer 75. For the intensive light from theprojector 71 to project on the screen 73 may be reflected by the mirror74 to generate highly bright spots on the array sensor 72, causing theidentification more difficult, an optical filter 78 is arranged in frontof the array sensor 72 to filter out the intensive light from theprojector 71, and thereby to specify the light source of the pointer 75from that of the projector 71, improving the identification andrepeatability.

Hardware of Pointing Input System

FIG. 9 shows a pointing input system 80 according to the presentinvention, in which a display system 81 is provided to display on ascreen 82, an array sensor 83 is prepared to shoot on the screen 82, anda pointer 87 is used to apply light spots on the screen 82 either in analignment procedure or for a pointing input. The array sensor 83 maycomprises Charge-Coupled Detector (CCD) or ComplementaryMetal-Oxide-Semiconductor (CMOS) sensor. In an alignment procedure, abuffer 84 is used to store a predetermined reference data that includesthe spatial information of a test pattern to be displayed on the screen82 or several specific positions on the screen 82 to be applied withlight spots thereon. Particularly, the spatial information includes therelative positions of several points in the test pattern or the severalspecific positions on the screen 82, for example the relative directionsand distances therebetween. The buffer 84 also stores an alignment datain an alignment procedure. The alignment data is generated by shootingthe test pattern or light spots at the several specific positions on thescreen 82 by the array sensor 83, and therefore includes the imageinformation of the shot test pattern or light spots. A processor 85 isprovided to identify and analyze the alignment data, for example withimage recognizing software and displacement and rotation calculationtool programs, in comparison with the reference data to evaluate thespatial relationship between the array sensor 83 and screen 82 and theoptical distortion of the optical lens in the array sensor 83. In thisprocess, for example, the processor 85 analyzes the relative positionsof several points in the test pattern or at the several specificpositions on the screen 82 between the alignment data and reference dataand their three-dimensional spatial relationship, to obtain a spatialrotation and displacement parameter. The processor 85 further comparesthe three-dimensional spatial coordinates of the several points todetermine an optical distortion parameter of the optical lens in thearray sensor 83 based on an optical lens distortion equation such asEQ-4. The optical distortion parameter and spatial rotation anddisplacement parameter are stored in a buffer 86 for use in a pointinginput. For a pointing input, a light spot is applied on the screen 82 bythe pointer 87, and the array sensor 83 shoots on the screen 82 togenerate a first data including the image information of the light spot.The first data is sent to an identification system 88, where it isidentified for the light spot and a second data including the positioninformation of the light spot is generated based on the opticaldistortion parameter and spatial rotation and displacement parameterprovided by the buffer 86. The second data is provided for the displaysystem 81 to apply a correlated output on the screen 82. In thisembodiment, the identification system 88 comprises a buffer 88 a tostore the first data generated by the array sensor 83, a register 88 cto provide an optical feature condition, and a processor 88 b to checkthe light spot from the first data to find out the nearby pixelssatisfying the optical feature condition to define an output spot, andto calculate the information including the size, average brightness,hue, length, width and area of the light spot that may be also includedin the second data.

The screen 82 may have a planar surface, a regularly curved surface, oran irregularly curved surface, and may be an active screen such as CRTscreen, LCD screen, plasma screen, and rear projection screen, or apassive screen such as scattering screen of front projector. All thedata to be used or processed may be stored and processed in a samecomputer system or separately stored and processed in different computersystems.

Flowchart of Alignment Procedure

As shown in FIG. 10, in a flowchart 90 of an alignment procedure for apointing input system according to the present invention, the shootingrange of an array sensor on a screen is first identified in step 91, aninput for alignment is applied on the screen in step 92, the screen isshot by the array sensor in step 93, an alignment data is generated instep 94, the alignment data is identified and compared with a referencedata in step 95, and an optical distortion parameter and a spatialrotation and displacement parameter is finally determined in step 96.The alignment data includes the image information of the input foralignment shot by the array sensor, and the reference data includes thepredetermined image information of the input for alignment that isprovided to apply on the screen, and therefore from the alignment dataand reference data, the spatial relationship between the array sensorand screen and the optical distortion of the lens in the array sensorare able to be determined. Specifically, the optical distortionparameter and spatial rotation and displacement parameter picture theoptical distortion of the optical lens in the array sensor and thespatial relationship between the array sensor and screen, and withwhich, the light spots applied on the screen after the alignmentprocedure are precisely identified for their positions.

Flowchart of Pointing Input Method

FIG. 11 shows a flowchart 100 of a pointing input method according tothe present invention. After the step 90 for alignment as shown in FIG.10 is completed, in step 101 a pointer is used to apply a light spot ona screen, the screen is shot by an array sensor in step 102, and a firstdata including the image information of the shot light spot is generatedin step 103. The first data is then identified in step 104 to generate asecond data including the position information of the light spot on thescreen based on the optical distortion parameter and spatial rotationand displacement parameter determined by the alignment procedure 90. Thesecond data is provided for an information system to generate acorrelated output applied on the screen by a display system in step 105.

Embodiment of Pointer

As shown in FIG. 12, a pointer 110 available for a pointing input systemaccording to the present invention comprises a set of light sources 112having different properties, several buttons 113, a roller 114 and aswitch 115. The light sources 112 are used for applying light spots on ascreen, and the buttons 113 and roller 114 are used to switch the lightsources 112 between different optical features, such as brightness, hue,size and shape. The optical features of the light sources 112 may beused for a trigger signal of an action, for example a pressing of a leftbutton of a mouse. The light sources 112 may output light beams havingone of several specific wavelengths or blinking with one of specificpatterns, to be distinguished from the environment light and the lightemitted by the display system, and to be sensitive by the array sensor,and it may also serve as an indication signal. Infrared Ray (IR) LED,visible light LED, and laser diode may be used for the light sources112. The switch 115 may be a contacting or non-contacting switch, todetermine the pointer 110 to touch on the screen, so as to producedifferent input effects, for example to be at an input state. If theswitch 115 is able to generate an analog output, it may be used todetermine a signal representative of the input pressure, so as tofeature a pen stroke. The pointer 110 may be used as a pen for directinputs on a screen, for example applying a light spot on a screen bypressing the switch 115, or drawing a line by continuously moving alight spot on a screen. The pointer 110 may also be used as a mouse forone click, double click, or drag on a screen.

Identification of Light Spot

FIG. 13 shows an illustrative diagram for an identification of a lightspot according to the present invention. The image of a light spotmapped onto an array sensor generally occupies a size of tens tohundreds of pixels, but not a single pixel, and therefore the image ofthe light spot captured by the array sensor will have a distribution ofoptical features such as the brightness. Based on a background noise 121and a threshold 122 to determine the input spot, for example byselecting the position 123 having the maximum of the optical feature, orthe position 124 having the center mass of the optical feature, or thecentral position 125 in the range having the optical feature close tothe threshold 122 as the position of the light spot, it is able toeliminate the interference of the background noise, and high stabilityand high precision are obtained for the light spot.

After identifying the position of a light spot, the position is storedto further monitor the continuous movement of the light spot and trackthe relative position of the light spot. Preferably, the relativeposition of the light spot is used for an information of determining atrigger signal representative of an action or a pen stroke.

While the present invention has been described in conjunction withpreferred embodiments thereof, it is evident that many alternatives,modifications and variations will be apparent to those skilled in theart. Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and scopethereof as set fourth in the appended claims.

1. A pointing input method comprising the steps of: preparing a displaysystem and a screen; arranging one or more array sensors for shooting onthe screen; performing an alignment procedure for obtaining an opticaldistortion parameter of the array sensor and a spatial rotation anddisplacement parameter; applying a light spot on the screen by apointer; shooting on the screen by the array sensor for generating afirst data including an image information of the light spot; generatinga second data including a position information of the light spot fromthe first data based on the optical distortion parameter and spatialrotation and displacement parameter; and applying a correlated output onthe screen based on the second data by the display system.
 2. The methodof claim 1, wherein the step of performing an alignment procedurecomprises the steps of: applying an input for alignment on the screen;shooting on the screen by the array sensor for generating an alignmentdata; and comparing the alignment data with a reference data forgenerating the optical distortion parameter and spatial rotation anddisplacement parameter.
 3. The method of claim 2, wherein the step ofapplying an input for alignment on the screen comprises displaying atest pattern on the screen by the display system or applying opticalspots on a plurality of positions on the screen.
 4. The method of claim3, wherein the test pattern comprises a chessboard pattern, a squarepattern, or a cross pattern.
 5. The method of claim 3, wherein thereference data comprises a plurality of spatial coordinates of the testpattern or the plurality of positions on the screen.
 6. The method ofclaim 2, wherein the step of performing an alignment procedure furthercomprises a bilinear interpolation for coordinates computations.
 7. Themethod of claim 1, further comprising identifying a shooting range ofthe array sensors on the screen.
 8. The method of claim 1, wherein thescreen comprises a planar surface, a regularly curved surface, or anirregularly curved surface.
 9. The method of claim 1, wherein the screencomprises a scattering screen, a CRT screen, an LCD screen, a plasmascreen or a rear projection screen.
 10. The method of claim 1, whereinthe pointer comprises a plurality of light sources having differentproperties, a plurality of buttons and a roller for generating varioustrigger signals representative of different actions.
 11. The method ofclaim 10, wherein the pointer further comprises a switch for determininga touch of the pointer to the screen for conducting different inputs.12. The method of claim 1, wherein the array sensor comprises an opticallens and an optical filter for mapping onto the array sensor andfiltering out an optical noise to thereby enhance identification effect.13. The method of claim 1, wherein the display system comprises a frontprojector or a rear projector.
 14. The method of claim 1, wherein thestep of generating a second data comprises the steps of: checking thefirst data for grouping a plurality of nearby pixels under a opticalfeature condition as a same spot; and obtaining an information includinga size, an average brightness, a hue, a length, a width and an area ofthe same spot.
 15. The method of claim 14, wherein the optical featurecondition comprises a brightness, a hue, a size and a shape.
 16. Themethod of claim 14, wherein the optical feature condition is used fordetermining a trigger signal of an action.
 17. The method of claim 1,further comprising monitoring a continuous movement of the light spotand tracking a relative position of the continuous movement.
 18. Themethod of claim 17, wherein the relative position is used fordetermining a trigger signal of an action or a pen stroke.
 19. Apointing input system comprising: an array sensor for shooting on ascreen; a first buffer for storing a reference data and an alignmentdata generated by shooting an input for alignment on the screen by thearray sensor; a processor for obtaining an optical distortion parameterand a spatial rotation and displacement parameter by analyzing thealignment data in comparison with the reference data; a second bufferfor storing the optical distortion parameter and spatial rotation anddisplacement parameter; a pointer for applying a light spot on thescreen for the array sensor to shoot to generate a first data includingan image information of the light spot; and an identification system forretrieving a second data including a position information of the lightspot from the first data based on the optical distortion parameter andspatial rotation and displacement parameter for a display system toapply a correlated output on the screen.
 20. The pointing input systemof claim 19, wherein the array sensor comprises a viewing window or alight beam for identifying a shooting range of the array sensor on thescreen.
 21. The pointing input system of claim 19, wherein the arraysensor comprises an optical lens and an optical filter for mapping ontothe array sensor and filtering out an optical noise to thereby enhanceidentification effect.
 22. The pointing input system of claim 19,wherein the pointer comprises a plurality of light sources havingdifferent properties, a plurality of buttons and a roller for generatingvarious trigger signals representative of different actions.
 23. Thepointing input system of claim 22, wherein the pointer further comprisesa switch for determining a touch of the pointer to the screen forconducting different inputs.
 24. The pointing input system of claim 19,wherein the identification system comprises: a register for providing anoptical feature condition; a third buffer for storing the first data;and a second processor for checking the first data to group a pluralityof nearby pixels under the optical feature condition as a same spot, andobtain an information including a size, an average brightness, a hue, alength, a width and an area of the same spot.
 25. The pointing inputsystem of claim 24, wherein the optical feature condition comprises abrightness, a hue, a size and a shape.
 26. The pointing input system ofclaim 24, wherein the optical feature condition is used for determininga trigger signal of an action.
 27. The pointing input system of claim24, wherein the identification system further monitors a continuousmovement of the light spot and tracks a relative position of thecontinuous movement.
 28. The pointing input system of claim 27, whereinthe relative position is used for determining a trigger signal of anaction or a pen stroke.
 29. The pointing input system of claim 19,wherein the display system comprises a front projector or a rearprojector.
 30. The pointing input system of claim 19, wherein the screencomprises a planar surface, a regularly curved surface, or anirregularly curved surface.
 31. The pointing input system of claim 19,wherein the screen comprises a scattering screen, a CRT screen, an LCDscreen, a plasma screen or a rear projection screen.